cotton breeding

1. Biotic and Abiotic
stresses in
Cotton. Presnted by :
VISHWAS ACHARYA
Breeding
legumes,
Oilseed and
Fiber Crops

2. Biotic Stress
Biotic stress occur to plants by
living organisms like
• Pathogen
• Insects
• Nematode
• Weeds and other plants

3. Insects
PINK BOLLWORM WHITE FLY
RED COTTON BUG
APHID
BOLLWORM MEALYBUG

4. Disease

5. Transgenic Plant for Biotic
Stress Resistance
Depending upon the type of pest to be controlled – whether
it Is a Lepidopteron, Coleopteron, etc. - the relevant gene
from the soil bacterium, Bacillus thuringiensis (Bt), is
isolated, the protein tested against the target larvae and if
found promising, the Bt gene is suitably modified and
introduced into the desired plant species by genetic-
engineering.

6. The transformed cotton lines are then screened to
identify the best ones expressing the Bt (Cry) protein(s)
to control the target pests.
These are used in further trait introgression breeding
program which allows this useful gene to be
introgressed into different Indian germplasm.

7. New Bt genes for new versions of
Bt- cotton
• Monsanto‟s Bt-cotton technology Bollgard-II
contains Cry1Ac + Cry2Ab.
• Dow agro Sciences are conducting trials with
Wide-strike (Cry1Ac + Cry1F + pat);
• Bayer, India have initiated trials with twin-link
(Cry1Ab + Cry2Ae + pat) and JK seeds have
started trials on Cry1Ac+Cry1EC.
• The vip3A gene is yet another toxin that is likely to
be pyramided with the existing toxins.

8. Abiotic Stresses
1. Drought stress
Prolonged dry spell due to uneven and erratic monsoon particularly under
rainfed condition will lead to rapid depletion in soil moisture. Drought stress gradually
develops and intensifies during the course of soil moisture decline resulting in
restricted growth and development in cotton. The current photosynthesis is impaired
and sustainability of leaf turgor may not be adequate to display an efficient canopy.
Cotton has to adapt or tolerate such adverse effects by various morphophysiological
traits. The most important physiological process is to possess higher water use
efficiency. This is mostly achieved by stomatal regulation. Prevention of water loss by
stomatal closure in restricting active transpiration from the leaf surface however tend
to increase leaf temperature as a reflex action. Plant has to adapt the optimum
physiological processes to ward off any harmful effects. Epicuticular wax on the leaf
surface may act as a protective mechanism.

9. Adaptive and tolerant morpho – physiological, biochemical
and anatomical traits in cotton .

10. 2.LOW LIGHT STRESS
Partial to full cloudy conditions
pertaining to active monsoon season (July to September in
Central India) cause low light stress affecting growth and
development of cotton. The low light stress may also extend
even in October, if the rainfed persists. The stress occurs due
to reduction in light intensity and total sun shine hours. The
stress occurs due to reduction in light intensity and total sun
shine hours. The light intensity on a full cloudy day may fall
below 400 µE and the sun shine hours may be drastically
restricted, sometimes even reaching zero.

11. • Increase in cotyledonary leaf area
• Increase in leaf area expansion
• Increase in leaf chlorphyll content per unit area
• Increases in shedding of fruiting parts
• Increase in light interception
• Decrease in biomass production
• Decrease in specific leaf weight (SLW)
The morpho – physiological effects of low light stress on cotton
are briefly mentioned below

12. 3.HIGH TEMPERATURE STRESS
The temperature range 26-32o C is desirable during day time
but the night should be cool during flowering and fruiting in cotton. This crop
is able to tolerate short periods of high temperature upto 43-45 oC if soil
moisture condition is favorable. High day temperature coupled with high night
temperature delay flowering. The associative trend of high temperature low
relative humidity is more harmful in desiccating the leaf surface due to sharp
increase in leaf temperature. High temperature regimes affect plant
metabolism by impairing membrane thermostability and photosynthetic
process. Enzyme activity is more sensitive and proteins may be denatured at
elevated temperatures. Plants tolerate high temperature by the accumulation of
low molecular weight 70 kda heat shock proteins. The other heat avoidable
mechanisms include light reflectance and transmittance to reduce the radiation
load and to maintain active transpiration cooling. Thick cuticle and hairiness
are desirable characters to minimize the heat stress effects.

13. 4.WATERLOGGING
Cotton in India is grown in different agroclimatic zones. In North
India more than 95 per cent of the crop is irrigated. Due to excessive canal irrigation, the water
table in parts of Haryana, Rajasthan and Punjab had risen to such a high level that it is
becoming difficult to grow cotton crop. In due course, rice or other crops may replace cotton in
these areas. In Central India, more than 70 per cent of the crop is grown under rainfed
conditions and often it suffers from waterlogging duration early and mid vegetative growth
stages. Even in South India where part of the crop is cultivated under irrigated condition and
rest under rainfed condition cotton experiences waterlogging at one or other stages of its life
cycle.
Flooding or submerging an air dry soil in water sets in motion
a series of physical, chemical and biological processes that profoundly influence the quality of
soil as a medium for plant growth. Flooding a dry soil destroys soil structure by disrupting the
aggregates. The soil pore space is totally water filled, and gas exchanges between soil and
atmosphere is virtually eliminated. Drastic restriction of gas exchange between flooded soil and
the atmosphere leads to depletion of molecular oxygen and accumulation in the soil of CO2,
methane and hydrogen. Deoxygenation and accumulation of the above gases in the rooting
medium cause either root damage or death of the plant. Thus, growth and productivity of the
plant will be affected.

14. 5. SALINTY STRESS

15. Mechanisum of Slinity tolerance
Although the mechanism of adaptation of plants
salinity is not clear, many basic physiological attributes including direct
modification of the influx and/ or efflux of ions such as K and Na
across the plasma membrane and tonoplast, synthesis of compatible
osmotica such as proline, other amino acids, soluble carbohydrates, and
glycine betaines, and modification of membrane composition have been
found to be important components of a salt tolerant phenotype. Sodium
accumulation in roots and leaves showed a linear increase upto10 dS
𝑚−1beyond which it was plateud. Contrarily, root K remained stable at
all salinity levels and leaf K content declined sharply at 5 and 10 dS m-
1. Tolerant varieties had high K/Na ratio compared to susceptible
varieties

16. Thanks!